Previously we have shown that a wide variety of animal cell culture lines can grow in serum-free medium containing classical hormones, growth factors, transport proteins, and attachment factors. Such substances and combinations thereof have now been used for the formulation of media suitable for the growth of primary human tumor cells. We have now devised hormonally defined media for human colon carcinoma cells, lymphoblastoid cells, lung epidermoid carcinoma cells, and lung adenocarcinoma cells. In all cases, the media are complex and the cells grow and display differentiated functions better than in serum containing media. (J)